Use of wireline tools in well operations



United StatesPatent O us. (:1. 166-315 10 Claims ABSTRACT THE DISCLOSURE The rate of descent of a wireline tool in a wellbore containing a column of heavy oil is increased by coating the tool with a surface active agentcapable of promoting the formation of a film of water on the tool and thereafter lowering the-tool in the wellbore.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to well operations and is particularly concerned with wireline operations carried out in wellsproducing heavy crude oil.

Description of the prior art Manyoil field operations require the lowering of wireline tools? into .wells through crude oil in the tubing or casing. Typical operations of this kind include the making of bottom-hole pressure measurements and temperature suryeys, the setting and releasingof packers and bridge plugs, the setting and retrieving of} gas lift valves, the running of logging tools of various types, the swabbing of-wells, and the like. Although suchoperations can often be carried out routinely, there are certain wells in which" the lowering of'wireline tool's! presents serious problems}; The rate of descent of such a-tool depends in part on the weight of the tool and the-density and viscosity of' the fluids present in the wellbore. In wells containing low gravity crude oils, this ratemay be so low that conventional wireline operations are not feasible. The difliculties thus encountered can be alleviated in some cases by using heavy sinker bars to increase the rate of descent but this is Often impractical because the length of the lubricator precludes the use of bars of suflicient weight. It may therefore be necessary to kill the well and pull theFtubing string or displace th'ejheavy oil with a lighter fluid through which the wireline tool can be lowered. This is costly and time consuming and hence is avoided wherever possible, often at the expense of needed tests or well improvements.

SUMMARY OF THE INVENTION This invention provides an improvedmethod for the lowering of wireline tools into wells containing low gravity crude oils 'and similar fluids. :In accordance with the invention, ,it has now been fou=d that the rate of descent of such-,-"tools can be impro ed significantly by coating the tools with surface active agents before they are lowered through the oil. Although the phenomena responsible for the improved results obtained are not fully understood, it appears that the presence of the sur- 3,474,867 Patented Oct. 28, 1969 DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of the invention involves the coating of a wireline tool'to be lowered into a wellbore containing a heavy crudeg oil or similar fluid with a surface active agent. This can be done by painting, spraying, dipping or smearing the ,tool with the surfactant before it is intro duced into thefwell. An alternate procedure involves pouring the surfactant into the lubricator and lowering the tool into it. In either case, it is preferable that the surface of the tool be clean and substantially free of oil before the surfactant is applied. Alcohol, naphtha or a similar solvent-may be used to wash off excess oil present and thus promote better adherence of the surfactant to the metallic surfaces of the tool.

A variety of different surface active agents are suitable for purposesof the invention. These may be anionic, cationic or nonionic compounds. In general, the agents found most effective are those marketed for use as water-"\....

wetting agents, oil in-Water emulsifiers, and water-in-oil demulsifiers. Typical agents which are generally effective include the .alkyl phenyl polyethoxythanols, the alkali metal salts of 'allyl esters of sulfosuccinic acid, the alkali metal salts of alkylaryl benzene sulfonic acids, the polyethylene oxide ethers of alkyl esters of aliphatic dicarboxylic acids"; the soluble salts of alkyl naphthalene sulfonic acids, the alkyl esters of polyalkylene glycols, the polyalkylene esters of fatty acids, the long chain amine hydrochlorides, the long chain polyamides, and the like. Particularly effective agents include polyoxyethylene glycol ethers of "dialkyldicarboxylic acids such as the polyoxyethylene glycol ethers of dioctyl maleate containing about 6.5 ethylene oxide groups per molecule and mixtures of alkali metal salts of sulfosuccinic acid with alkyl phenyl polyoxtyethanols such as mixtures containing about 6 parts of sodium dioctylsulfosuccinate, about 3 parts of sodium diheigyflsulfosuccinate, and about 1 part of isooctyl phenyl polyonyethanol containing from 9 to 10 ethylene oxide groups}per molecule.

The surface active agents employed for purposesof the invention are available as liquids of various concentrations and as pastes or solids. The use of viscous, highly adherent liq'uid surfactants or pastes is generally preferred but aqueous surfactant solutions having concentrations in excess ofi about 50% by weight may be advantageous in certain cases. The pastes are particularly effective in deep wells where a relatively thick coating of the surfactant whiehwill persist for a prolonged period is'desired. Where a paste or highly concentrated liquid surfactant is used, it is sometimes advantageous to wet the tool with water after the surfactant has been applied and before the tool is introduced into the heavy oil. This provides an initial film of water to facilitate movement of the tool through the heavy oil. A reservoir at the lower end of the tool for providing small amounts of additional water as the tool is lowered may also be advantageous in deep wells where the heavy oil is essentially free of dispersed water.

After the surface active agent has been applied to the surface of the wireline tool, the tool is lowered in the heavy oil in the wellbore. Dispersed water present in the oil tends to accumulate on the surface of the surfactant coating and thus forms a water film betwene the oil and the tool. If water was used to wet the surfactant-coated tool before it was introduced into the oil; the dispersed water tends to augment the existing film. This film of water isolates the tool surface from theiheavy oil and produces a substantial drop in hydraulic friction as the device is lowered through the column of oil. This in turn results in an increase in the rate at which the tool descends through the oil. Sinker bars can be used in the conventional manner to obtain a further increase if desired. Once the tool has reached the desired level and the contemplated operation has been carried out, it can be withdrawn by means of the wireline without difficulty. The advantages of the method of the invention are exemplified by the results obtained in gas lift wells containing a heavy crude oil with a 14.2 API gravity. Earlier efiorts to change the gas lift valves in these wells by wireline operations had not been successful. The rate at which the wireline apparatus moved downwardly through the heavy oil was so slow that such operations were not feasible. It was found that smearing of the tool with about a half pint of a viscous surface active agent containing as the active ingredient a polyethylene glycol ether of dioctyl maleate having about 6.5 ethylene oxide groups per molecule before it was introduced into the well resulted in rapid movement of the tool downwardly through the heavy oil. This use of a surface active agent permitted the routine changeout of gas liftvalves in these wells without difficulty. The necessity for pulling the tubing strings from the wells was avoided and substantial savings in both time and money were realized.

What is claimed is:

1. A method for increasing the rate of descent of a wireline tool in a well containing a heavyoil which com- 85 prises coating the surface of said tool with a surface active agent capable of promoting the formation of afilm of water on the tool and thereafter lowering said tool in said well.

2. A method as defined by claim 1 wherein said surface active agent comprises an alkyl phenyl polyethoxyethanol.

3. A method as defined by claim 1 wherein said surface active agent comprises a polyoxyethylene glycol ether of a dialkyl carboxylic acid.

4. A method as defined by claim 1 wherein'saidsurface active agent is applied to the surface of said tool as a paste.

5. A method as defined by claim 1 wherein water is applied to said tool after said surface is coated with said surface active agent.

6'. A method as defined by claim 1 wherein said surface active agentis a viscous liquid.

7. A method as defined by claim -1 wherein said surface active-agent is a polyethylene glycol ether ofdioctyl maleate containing about 6.5 ethyleneoxide groups per molecule.

8. A method as defined by claim 1 wherein said-.surface active agent is a mixture of about 6 parts of sodium dioctylsulfosuccinate, about 3 parts of sodium dihexylsulfosuccinate, and about 1 part of isoctyl phenyl polyethoxyethanol containing from 9 to 10 ethylene oxidevgroups per molecule.

9. A method as defined by claim 1 wherein said wireline tool is lowered into said well through a lubricator and said surface active agent is applied to said tool in the lubricator.

10. A method as defined by claim 1 wherein said surface active agentcomprises an alkali metal salt of an alkyl ester of sulfosuccinate acid.

References Cited UNITED STATES PATENTS 2,567,475 9/1951 Hall 166-153 X 2,793,698 5/1957 Tausch 166-46 3,011,197 12/1961 Nehse et al. l5-.l04.06 3,216,435 11/1965 Poettmann 187-13 3,230,919 1/1966 Crawford 137--l3 X CHARLES E. OCONNELL, Primary Examiner IAN A. CALVERT, Assistant Examiner US. Cl. X.R. 137-13 

